# Econ

posted by
**Jack**
.

A firm faces the following sales function:

Q=5,000-10P+40A+PA-0.8A^2-0.5P^2

where Q is sales, P is price(dollars), and A is advertising expenditures (in hundreds of dollars). Calculate the price and advertising levels that maximize sales.

I don't know what to do with it with three variables.